package com.lcx.demo.nioday01;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;

/*
 *一、使用NIO完成网络通信的三个核心
 *
 * 1.通道（Channel)：负责连接
 *  java.nio.channels.Channel 接口：
 *       |--SelectableChannel
 *           |--SocketChannel
 *           |--ServerSocketChannel
 *           |--DatagramChannel
 *
 *           |--Pipe.SinkChannel
 *           |--Pipe.SourceChannel
 *
 * 2.缓冲区（Buffer）：负责数据的存取
 *
 * 3.选择器（Selector）：是SelectableChannel的多路复用器。用于监控SelectableChannel的IO状况
 */
public class TestNonBlockingNIO {

    //客户端
    @Test
    public void client() throws IOException {
        //1.获取通道
        SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9876));

        //2.切换非阻塞模式
        sChannel.configureBlocking(false);

        //分配指定大小的缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);

        //发送数据给服务端
        buf.put(new Date().toString().getBytes());
        buf.flip();
        sChannel.write(buf);
        buf.clear();

        //  while (sChannel.read(buf)!=-1){
//          buf.flip();
//          System.out.println(new String(buf.array()));
//          buf.clear();
//          }

        //关闭通道
        sChannel.close();

    }

    @Test
    public void server(){

        try {
            //获取通道
            ServerSocketChannel open = ServerSocketChannel.open();

            //切换非阻塞模式
            open.configureBlocking(false);

            //绑定链接
            open.bind(new InetSocketAddress(9876));

            //获取选择器
            Selector selector = Selector.open();

            //将通道注册到选择器上，并且指定“监听接受事件"
            open.register(selector, SelectionKey.OP_ACCEPT);

            //轮询式的获取选择器上的已经”准备就绪“的事件
            while (selector.select()>0){
                //获取当前选择器中所有注册的”选择键（已就绪的监听事件）“
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();

                while(iterator.hasNext()){
                    //获取准备就绪的事件
                    SelectionKey selectionKey = iterator.next();

                    //判断是什么事件准备就绪
                    if (selectionKey.isAcceptable()){
                        //若接受就绪，获取客户端连接
                        SocketChannel socketChannel = open.accept();
                        //切换非阻塞模式
                        socketChannel.configureBlocking(false);

                        //将该通道注册到选择器上
                        socketChannel.register(selector,SelectionKey.OP_READ);

//                        ByteBuffer allocate = ByteBuffer.allocate(1024);
//                        allocate.put("hhhhhh".getBytes());
//
//                        allocate.flip();
//                        ByteBuffer[] byteBuffers = {allocate};
//                        socketChannel.write(byteBuffers,0, byteBuffers.length);

                    }else if (selectionKey.isReadable()){
                        //获取当前选择器上”读就绪“状态的通道
                        SocketChannel channel = (SocketChannel) selectionKey.channel();

                        //读取数据
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

                        int len = 0;
                        while ((len=channel.read(byteBuffer))!=-1){
                            byteBuffer.flip();
                            System.out.println(new String(byteBuffer.array(),0,len));
                            byteBuffer.clear();
                        }
                    }
                    //取消选择器 SelectionKey
                    iterator.remove();
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
